It seems like Rome has had a special fascination with sundials -- linking time and the cosmos with accessible, aesthetic objects.

This Baroque ornament serves as a timepiece for pedestrians passing by the Palazzo Spada in central Rome. It was either designed by, or in the style of Borromini, whose Prospettiva (an illusionistic play of space and perspective) is in the adjacent garden.

Not a dial, but a full façade -- this sun clock rises above the Collegio Romano in the complex of the original Jesuit university. Established by Ignatius Loyola in 1551, it realized his vision of imparting the liberal arts -- sciences, art, literature, philosophy -- to youth and the Jesuit clergy.

The synthesis of science and theology goes a step further with the instrument below:

You're looking at the south transept in the church of Santa Maria degli Angeli, a Mannerist masterpeice which Michelangelo designed into part of the enormous Diocletian Baths of the 3rd century. In the 18th century (age of Enlightenment) Pope Clement XI ordered that a "meridian" (true to the north-south planetary meridian) be installed with a corresponding aperture for the sun's beam (red arrow above, 1st photo below) placed so that it would cross the meridian (just above red line on floor above, 2nd photo below) everyday at precisely noon, progressing diagonally cross the church floor with the seasons.

The primary theological purpose was to document the spring equinox, which determined the date of Easter (first Sunday folowing the full moon after the spring equinox). In addition, meridian inscriptions included constellations and signs of the zodiac. I'm fascinated by the cosmography this instrument reveals of the eighteenth-century mind!

 

The above diagram illustrates an ancient Roman sun clock of majestic proportions. It's gnomon (pointer) was a 22-meter tall Egyptian obelisk from the 6th century BC, which Emperor Augustus brought to Rome to celebrate his vicotry over Cleopatra. The large bronze declinations of the hours stretched across the Campus Martius (field of Mars, Rome's temple district in ancient times).

Today, the Montecitorio Obelisk still stands (first photo), though the bronze inscription (second photo) is buried under nearby buildings.

I include this first-century inscription -- Imperial roman letters carved into granite on the base of the Montecitorio Obelisk -- to prove that I am still looking at letters. Carved inscriptions also have a wonderful play with the sun's light and shadow during the hours of the day!

And finally, does this qualify as a sundial? Looking like it's melting in Rome's midday sun, the oversized replica is part of a current Salvador Dali exhibition.